Ethylene-propylene terpolymer and crystalline 1,2 polybutadiene
United States Patent 3891724
An ethylene-propylene rubber composition comprising 3 to 50 % by weight of at least one 1,2-polybutadiene having a 1,2-addition unit content of at least 70 %, a crystallinity of at least 5 % and an intrinsic viscosity [η] as measured in toluene at 30°C of at least 0.7 dl/g, and 97 to 50 % by weight of at least one ethylene-propylene-diene terpolymer. The above composition has a high vulcanization rate, a high green strength and an excellent processability.
US Patent References:
PROCESS FOR THE CATALYTIC PREPARATION OF 1,2-POLYBUTADIENE HAVING A HIGH PERCENTAGE OF VINYL CONFIGURATION
Ichikawa et al. - March 1970 - 3498963
/3741931.html
Martin et al. - June 1973 - 3741931
PROCESS FOR THE CATALYTIC PREPARATION OF 1,2-POLYBUTADIENE HAVING A HIGH PERCENTAGE OF VINYL CONFIGURATION
Ichikawa et al. - March 1970 - 3498963
/3741931.html
Martin et al. - June 1973 - 3741931
Inventors:
Yaeda, Yasuyuki (Yokkaichi, JA)
Chikatsu, Yoshishige (Yokkaichi, JA)
Ando, Noriaki (Yokkaichi, JA)
Sakata, Ryuichi (Kobe, JA)
Chikatsu, Yoshishige (Yokkaichi, JA)
Ando, Noriaki (Yokkaichi, JA)
Sakata, Ryuichi (Kobe, JA)
Application Number:
05/423851
Publication Date:
06/24/1975
Filing Date:
12/11/1973
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Export Citation:
Assignee:
Japan Synthetic Rubber Co., Limited (Tokyo, JA)
Primary Class:
Other Classes:
525/211, 521/140
International Classes:
C08L23/16; C08L23/00; C08F45/54; C08F29/12
Field of Search:
260/888,889,2.5HA,29.7,29.7T,29.7SQ,33.6,33.6AQ,33.6PO,45.7R,42.21,42.31
Primary Examiner:
Tillman, Murray
Assistant Examiner:
Ziegler J.
Attorney, Agent or Firm:
Ladas, Parry, Von Gehr, Goldsmith & Deschamps
Claims:
What is claimed is
1. An ethylene-propylene rubber composition comprising 3 to 50 % by weight of at least one 1,2-polybutadiene having a 1,2-addition unit content of at least 70 %, a crystallinity of at least 5 % and an intrinsic viscosity of at least 0.7 dl/g as measured in toluene at 30°C, and 97 to 50 % by weight of at least one ethylene-propylenediene terpolymer rubber.
2. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a 1,2-addition unit content of at least 85 %.
3. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a crystallinity of 5 to 50 %.
4. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a crystallinity of 10 to 30 %.
5. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has an intrinsic viscosity of at least 1.0 dl/g as measured in toluene at 30°C.
6. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a 1,2-addition unit content of at least 85 %, a crystallinity of 10 to 30 % and an intrinsic viscosity of at least 1.0 dl/g as measured in toluene at 30°C.
7. An ethylene-propylene rubber composition according to claim 1, wherein the terpolymer rubber has an ethylene content of 50 to 80 % by weight, a propylene content of 50 to 20 % by weight and a diene content of up to 5 % by weight.
8. An ethylene-propylene rubber composition according to claim 1, which further contains at least one compounding ingredient selected from the group consisting of reinforcing agents, fillers, extender oils, pigments, vulcanizing agents, vulcanization accelerators, vulcanization activators, antioxidants, ultraviolet absorbers, blowing agents, odorants and softening agents.
9. A vulcanizate of the rubber composition according to claim 1.
1. An ethylene-propylene rubber composition comprising 3 to 50 % by weight of at least one 1,2-polybutadiene having a 1,2-addition unit content of at least 70 %, a crystallinity of at least 5 % and an intrinsic viscosity of at least 0.7 dl/g as measured in toluene at 30°C, and 97 to 50 % by weight of at least one ethylene-propylenediene terpolymer rubber.
2. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a 1,2-addition unit content of at least 85 %.
3. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a crystallinity of 5 to 50 %.
4. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a crystallinity of 10 to 30 %.
5. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has an intrinsic viscosity of at least 1.0 dl/g as measured in toluene at 30°C.
6. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a 1,2-addition unit content of at least 85 %, a crystallinity of 10 to 30 % and an intrinsic viscosity of at least 1.0 dl/g as measured in toluene at 30°C.
7. An ethylene-propylene rubber composition according to claim 1, wherein the terpolymer rubber has an ethylene content of 50 to 80 % by weight, a propylene content of 50 to 20 % by weight and a diene content of up to 5 % by weight.
8. An ethylene-propylene rubber composition according to claim 1, which further contains at least one compounding ingredient selected from the group consisting of reinforcing agents, fillers, extender oils, pigments, vulcanizing agents, vulcanization accelerators, vulcanization activators, antioxidants, ultraviolet absorbers, blowing agents, odorants and softening agents.
9. A vulcanizate of the rubber composition according to claim 1.
Description:
This invention relates to an ethylene-propylene rubber composition. More particularly, this invention relates to a rubber composition having a high vulcanization rate, a high green strength and an excellent processability, comprising a polybutadiene having a 1,2-addition unit content of at least 70 % (referred to hereinafter as 1,2-polybutadiene) and an ethylenepropylene-diene terpolymer (referred to hereinafter as EPDM).
Commercially available ethylene-propylene rubbers, particularly EPDM are excellent in thermal resistance, ageing resistance, weather resistance and ozone resistance, have good electric properties and good cold brittleness, and are similar to natural rubber particularly in behavior of elastic properties on temperatures. Therefore, the EPDM can be vulcanized with sulfur similarly to conventional rubbers. Further, the EPDM can be produced at considerably low cost as compared with conventional diene rubbers, because the starting materials, ethylene and propylene, for the EPDM are supplied in large amounts and at low cost by petrochemical industry. In addition, the EPDM can be extended with a large amount of oil. Thus, the EPDM is advantageous even in the aspect of economy, and hence, is expected as wide-use rubbers in future. However, the EPDM is greatly disadvantageous in processability, i.e., the vulcanization rate is very low and the stickiness is low. Therefore, EPDM is greatly limited in practical use.
The present inventors have extensive research on EPDM having no such disadvantages to find that by blending the specific 1,2-polybutadiene with the EPDM, the above-mentioned disadvantages of the EPDM are removed, the extrudability of the EPDM is improved, and the rubbery properties of vulcanizate of the EPDM are hardly impaired or rather improved.
An object of this invention is to provide an EPDM composition having improved properties.
A further object of the invention is to provide an EPDM composition having a high vulcanization rate, a high green strength and an excellent processability.
A still further object of the invention is to provide an EPDM composition comprising an EPDM and 1,2-polybutadiene.
Other objects and advantages of the invention will be apparent from the following description.
According to this invention, there is provided an EPDM composition comprising 97 to 50 % by weight of at least one EPDM and 3 to 50 % by weight of at least one 1,2-polybutadiene having a 1,2-addition unit content of at least 70 %, a crystallinity of at least 5 % and an intrinsic viscosity of at least 0.7 dl/g as measured in toluene at 30°C.
The 1,2-polybutadienes used in this invention have a 1,2-addition unit content of at least 70 %, preferably at least 85 %. When the 1,2-addition unit content is less than 70 %, the green strength is too low. Further, the crystallinity of the 1,2-polybutadienes is at least 5 %, preferably 5 to 50 %, particularly preferably 10 to 30 %, in view of ease of mixing. When the crystallinity is less than 5 %, the green strength-improving effect is too small, and the physical properties of the vulcanizate of such a composition are not satisfactory. Furthermore, the 1,2-polybutadienes have an intrinsic viscosity as measured in toluene at 30°C of at least 0.7 dl/g, preferably at least 1.0 dl/g. When the intrinsic viscosity is less than 0.7 dl/g, the green strength of the composition is unsatisfactory, and the physical properties of vulcanizate, particularly modulus, are inferior. 1,2-Polybutadienes satisfying the above-mentioned conditions can be produced by the methods disclosed in U.S. Pat. Nos. 3,498,963 and 3,522,332. The above 1,2-polybutadienes may be used alone or in admixture of two or more, or in admixture with such an amount of other 1,2-polybutadienes as not to impair the effect of the invention.
In this invention, the amount of the 1,2-polybutadienes used is 3 to 50 % by weight based on the weight of the rubber compsotion of this invention. When the amount is more than 50 %, the composition is not desirable in respects of resilience and permanent set. When the amount is less than 3 % by weight, substantially no effect of this invention is obtained.
The EPDM used in this invention may be any of those which are commercially available, though those comprising 50 to 80 % by weight of ethylene, 50 to 20 % by weight of propylene and up to 5 % by weight of diene (corresponding to an iodine number of about 50) are preferably used in general. Typical examples of the diene include 1,4-hexadiene, dicyclopentadiene, 5-methylene- 2-norbornene, 5-ethylidene-2-norbornene, 1,5cyclooctadiene, etc. When the propylene content is less than 30 % by weight, the EPDM per se has a great green strength, and in addition, the vulcanization rate and processability of the EPDM are also improved by blending the 1,2-polybutadienes therewith according to this invention. The EPDM may be used alone or in admixture of two or more.
In this invention, the 1,2polybutadiene and the EPDM may be mixed by any known method, for example, by mixing a solution of the 1,2polybutadiene with a solution of the EPDM and then removing the solvents from the resulting mixture, or by conventionally mechanically mixing the 1,2-polybutadiene with the EPDM each in the form of solid by means of, for example, rolls, Banbury's mixer, kneader-blender, or the like.
It is, of course, possible to incorporate into the rubber composition of this invention at least one conventional compounding ingredient, such as reinforcing agents, fillers, extender oils, pigments, vulcanizing agents, vulcanization accelerators, vulcanization activators, antioxidants, ultraviolet absorbers, blowing agents, odorants, softening agents, etc.
The rubber composition of this invention has a high green strength, a high vulcanization rate and a greatly improved processability, such as high extrusion rate and a high stickiness. Further, the vulcanizate of the rubber composition is greatly excellent in hardness and resistance to crack-growing. In addition, the rubbery properties of the EPDM, for instance, resilience and permanent set, are not so much impaired. Therefore, the rubber composition of this invention can be used as elements which are very useful in industry as novel ethylene-propylene type rubber composition.
The invention is further explained below in more detail referring to the following Examples, which are not by way of limitation, but by way of illustration.
The micro-structures of the 1,2-polybutadienes used in the Examples were measured by the infrared absorption spectrum method of D. Morero et al. (Chimie et Ind., 41, 758 (1959)). The crystallinity was determined by the density measurement method in which the following equation was used: ##EQU1## wherein d: density of the specimen measured at 20°C,
d cr : density of the crystalline region,
d am : density of the amorphous region,
X: crystallinity in per cent.
The value of d cr used was that of the crystalline 1,2-polybutadiene calculated by Natta from X-ray experiments to be 0.963 (G. Natta, J. Polymer Sci., 20, 251 (1956)). The value of d am used was 0.892 or the density of the 1,2-polybutadiene obtained by the synthesizing process proposed in U.S. Pat. No. 3,498,963 and found to be completely amorphous by X-ray analysis. The iodine number of the EPDM was determined by the following equation: ##EQU2## In the examples, parts are by weight unless otherwise specified.
EXAMPLE 1
1,2-Polybutadiene having a 1,2-addition unit content of 92.0 %, a crystallinity of 25 % and an intrinsic viscosity of 1.30 dl/g as measured in toluene at 30 °C (referred to hereinafter as 1,2-polybutadiene (A) and an ethylene-propylene-5-ethylidene-2-norbornene terpolymer rubber having a propylene content of 43 % by weight and an iodine number of 15 (referred to hereinafter as EPDM (A)) were mixed by a Banbury's mixer (in the case of vulcanizing system, they were mixed by rolls) with the prescription shown in Table 1 to prepare rubber compositions.
Table 1 ____________________________________________________________ ______________ Sample No. Ingre- 1 2 3 4 5 6 dients blended ____________________________________________________________ ______________ EPDM (A) (part) 100 95 90 85 70 60 1,2-Polybutadiene (A) (part) 0 5 10 15 30 40 Carbon black (HAF) (part) 67.5 67.5 67.5 67.5 67.5 67.5 Naphthenic extender oil 35 35 35 35 35 35 (part) Zinc oxide (part) 5 5 5 5 5 5 Stearic acid (part) 1 1 1 1 1 1 Accelerate CZ (N-cyclo- hexyl-2-benzothiazyl- 2.5 2.5 2.5 2.5 2.5 2.5 sulfenamide) (part) Sulfur (part) 1.5 1.5 1.5 1.5 1.5 1.5 ____________________________________________________________ ______________ Remarks Com- para- tive Examples Ex- ample ____________________________________________________________ ______________
The resulting rubber compositions were subjected to measurement of vulcanization rate, green strength, extrusion rate, and die shrinkage, and vulcanizates obtained by vulcanizing the rubber compositions at 160°C for 15 min. were subjected to measurement of various physical properties to obtain the results shown in Table 2.
Table 2 ____________________________________________________________ ______________ Sample No. Measure- 1 2 3 4 5 6 ment item ____________________________________________________________ ______________ Vulcanization Rate (Oscillating disk rheometer) T90 (min. sec) 15'24" 14'12" 13'24" 12'42" 11'48" 11'12" T90-T10 (min, sec) 10'05" 9'28" 8'12" 7'26" 6'00" 5'28" Green strength (at room temperature) 100 % modulus (kg/cm 2 ) 3.7 5.3 7.0 8.4 13.5 20.0 (Tensile strength (kg/cm 2 ) 4.3 5.8 7.5 9.6 17.1 29.1 Elongation (%) 400 390 380 380 380 390 (at 40°C) 100 % modulus (kg/cm 2 ) 2.9 3.1 3.5 4.2 8.0 13.0 Tensile strength (kg/cm 2 ) 3.7 3.8 3.9 4.8 9.9 17.2 Elongation (%) 410 390 360 370 410 420 (at 80°C) 100 % modulus (kg/cm 2 ) 1.1 1.2 1.3 1.6 2.6 3.5 Tensile strength (kg/cm 2 ) 1.5 1.6 1.6 1.9 3.5 4.8 Elongation (%) 390 360 340 340 330 310 Extrusion test (1) Extrusion rate (cc/min) 244.0 265.0 290.5 288.0 271.0 -- Die shrinkage (%) 41.7 41.5 41.0 40.5 40.3 -- Physical properties of vulcanizate 300 % modulus (kg/cm 2 ) 130 131 133 134 138 142 Tensile strength (kg/cm 2 ) 183 187 189 186 166 168 Elongation (%) 410 420 420 410 370 360 Hardness (JIS Hs) 69 71 73 74 77 79 Tear strength (kg/cm) 49 53 54 54 55 57 Resilience (%) 47 42 38 35 27 28 Compression permanent set (%) 18 18 18 19 21 25 Crack-growing (2) 500 times 5.3 -- 2.8 -- 4.1 -- 1000 times 9.3 -- 4.2 -- 5.7 -- 3000 times 15.4 -- 8.8 -- 9.7 -- ____________________________________________________________ ______________ Remarks Compara- Examples tive Example ____________________________________________________________ ______________ Note: (1) Extruder conditions were as follows: Barrel temperature: 70°C Die temperature: 105°C Screw revolution: 21 rpm (2) Numerals show the lengths of cracks (mm).
EXAMPLE 2
The 1,2-polybutadiene (A) and the EPDM (A) used in Example 1 were mixed with the prescription shown in Table 3 by means of a Banbury's mixer (in the case of vulcanizing system, they were mixed by rolls) to obtain rubber compositions.
Table 3 ____________________________________________________________ ______________ Sample No. Ingre- dients 7 8 9 10 11 blended ____________________________________________________________ ______________ EPDM (A) (part) 100 95 90 85 70 1,2-Polybuta- diene (A) (part) 0 5 10 15 30 Carbon black (HAF) (part) 67.5 67.5 67.5 67.5 67.5 Naphthenic extender oil (part) 35 35 35 35 35 Zinc oxide (part) 5 5 5 5 5 Stearic acid (part) 1 1 1 1 1 Accelerator TS (tetramethylthiuram monosulfide) (part) 1.5 1.5 1.5 1.5 1.5 Accelerator M (2-mercaptobenzo- thiazole) (part) 0.5 0.5 0.5 0.5 0.5 Sulfur (part) 1.5 1.5 1.5 1.5 1.5 ____________________________________________________________ ______________ Remarks Compara- tive Ex- Examples ample ____________________________________________________________ ______________
The resulting rubber compositions were subjected to measurement of vulcanization rate, green strength and extursion rate to obtain the results shown in Table 4.
Table 4 ____________________________________________________________ ______________ Sample No. 7 8 9 10 11 Measurement item ____________________________________________________________ ______________ Vulcanization rate (Oscillating disk rheometer) T90 (min, sec) 11'00" 8'06" 8'06" 7'24" 7'48" T90-T10 (min, sec) 6'24" 4'06" 3'48" 3'36" 4'24" Green strength (at room temperature) Tensile strength (kg/cm 2 ) 5.3 5.8 5.9 7.0 14.8 Elongation (%) 290 220 210 200 220 (at 50°C) Tensile strength (kg/cm 2 ) 3.5 4.0 4.4 4.8 11.0 Elongation (%) 420 330 300 200 260 (at 80°C) Tensile strength (kg/cm 2 ) 1.2 1.2 1.2 1.3 1.4 Elongation (%) 470 430 360 340 240 Extrusion rate (1) (cc/min) 180.3 198.4 202.3 205.6 212.5 Remarks Compara- Examples tive Example ____________________________________________________________ ______________ (1) Extruder conditions were as follows: Barrel temperature: 70°C Die temperature: 110°C Screw revolution: 21 rpm.
EXAMPLE 3
The 1,2-polybutadiene (A) used in Example 1, 1,2-polybutadiene having a 1,2-addition unit content of 89.7 %, a crystallinity of 15 % and an intrinsic viscosity of 1.85 dl/g as measured in toluene at 30°C (referred to hereinafter as 1,2-polybutadiene (B)), 1,2-polybutadiene having a 1,2-addition unit content of 86.7 %, a crystallinity of 0 % and an intrinsic viscosity of 2.05 dl/g as measured in toluene at 30°C (hereinafter referred to as 1,2-polybutadiene (X)) for comparison, the EPDM (A) used in Example 1 and an ethylene-propylene-5-ethylidene- 2-norbornene terpolymer rubber having a propylene content of 27 % by weight, and an iodine number of 15 (referred to hereinafter as EPDM (B)) were used in amounts shown in Table 5. These components were mixed with the prescription shown in Table 5 by means of a Banbury's mixer (in the case of vulcanizing system, by means of rolls) to prepare rubber compositions.
Table 5 ____________________________________________________________ ______________ Sample No. 7 12 13 14 15 16 17 18 19 20 21 22 23 24 Ingredients blended ____________________________________________________________ ______________ EPDM (A) (part) 100 90 90 90 70 70 70 -- -- -- -- -- -- -- EPDM (B) (part) -- -- -- -- -- -- -- 100 90 90 90 70 70 70 1,2-Polybuta- -diene (A) (part) -- 10 -- -- 30 -- -- -- 10 -- -- 30 -- -- " (B) (part) -- -- 10 -- -- 30 -- -- -- 10 -- -- 30 -- " (X) (part) -- -- -- 10 -- -- 30 -- -- -- 10 -- -- 30 Carbon black (HAF) (part) 67.5 Naphthenic extender oil (part) 35 Zinc oxide (part) 5 Stearic acid (part) 1 The same as left Accelerator TS (part) 1.5 Accelerator M (part) 0.5 Sulfur (part) 1.5 ____________________________________________________________ ______________ Remarks Comp Example Comp. Example Comp. Example Comp. Example Comp. Ex. Ex. Ex. Ex. Ex. ____________________________________________________________ ______________
The resulting rubber compositions were subjected to measurement of vulcanization rate, and green strength, and the vulcanizates obtained by vulcanizing the compositions at 160°C for 30 min. were subjected to measurement of hardness, crack-growth, resilience, and compression permanent set. The results obtained are shown in Table 6.
Table 6 ____________________________________________________________ ______________ Sample No. Measure- ment items 7 12 13 14 15 16 17 18 19 20 21 22 23 24 ____________________________________________________________ ______________ Vulcaniz- ation rate (Oscillat- ing disk rheometer) T90 11'00" 8'06" 8'00" 7'30" 8'18" 8'54" 7'48" 11'24" 8'24" 7'54" 6'30" 8'48" 9'00" 7'42" min, sec) T90-T10 6'24" 3'48" 3'36" 3'30" 4'00" 4'36" 4'06" 4'42" 3'42" 3'24" 2'12" 4'00" 4'10" 3'48" (min, sec) Green strength (at room temp.) Tensile strength (kg/cm 2 ) 5.3 5.9 5.4 4.9 13.0 8.6 5.0 34 30 32 32 29 29 28 Elongation -(%) 290 210 240 290 100 250 270 1150 1160 1200 1220 430 1090 1360 (at 50°C) Tensile strength (kg/cm 2 ) 3.5 2.8 2.6 2.6 7.1 3.3 2.6 3.0 4.2 3.8 2.7 8.2 4.0 2.4 Elongation (%) 420 300 340 320 120 280 340 340 260 280 300 120 260 260 at (80°C) Tensile strength (kg/cm 2 ) 1.2 1.2 1.2 1.2 2.1 1.2 1.3 1.7 1.7 1.7 1.5 2.8 1.7 1.5 Elongation (%) 470 360 420 460 220 300 380 380 340 320 320 180 260 260 Physical properties of vulcan- -izate Hardness (JIS Hs) 70 73 74 75 78 75 75 70 75 76 75 79 77 77 Crack- growth* 100 times 0.9 0.2 0.2 0.2 -- -- -- 3.7 -- -- -- 0.4 0.6 0.7 1000 times 5.2 0.7 0.6 0.8 -- -- -- 11.0 -- -- -- 1.1 1.4 1.6 10000 times 15.3 3.3 2.6 3.7 -- -- -- ** -- -- -- 5.3 6.0 16.9 Resilience (%) 50 36 38 41 35 36 41 58 42 43 45 40 41 45 Compress- ion perm- anent set (%) 26 25 27 27 31 32 31 33 21 19 20 24 33 27 30 ____________________________________________________________ ______________ Remarks Comp. Example Comp. Example Comp. Example Comp. Example Comp. Ex. Ex. Ex. Ex. Ex. ____________________________________________________________ ______________ Note: *Numerals refer to lengths of cracks (mm). **Totally cracked.
EXAMPLE 4
1,2-Polybutadiene having a 1,2-addition unit content of 92.0 %, a crystallinity of 24 % and an intrinsic viscosity of 1.57 dl/g as measured in toluene at 30°C (referred to hereinafter as 1,2-polybutadiene (C)) and an ethylene-propylene-5-ethylidene-2-norbornene terpolymer rubber having a propylene content of 42 % by weight and an iodine number of 20 (referred to hereinafter as EPDM (C)) were mixed with the prescription shown in Table 7 by means of a Banbury's mixer (in the case of vulcanizing system, by means of rolls) to prepare rubber compositions.
Table 7 ______________________________________ Sample No. Ingredients blended 25 26 ______________________________________ EPDM (C) (part) 100 90 1,2-Polybutadiene (C) (part) 0 10 Carbon black (HAF) (part) 5 5 Magnesium silicate (part) 60 60 Hard clay (part) 60 60 Naphthenic extender oil (part) 6 6 Paraffin wax (part) 5 5 Zinc oxide (part) 5 5 Stearic acid (part) 1 1 Accelerator M (part) 2 2 "TT (tetramethylthiuram disulfide) (part) 0.5 0.5 Accelerator TRA (dipentamethylenethiuram (tetrasulfide) (part) 0.75 0.75 Sulfur (part) 1.5 1.5 Remarks Compara- Example tive Example ______________________________________
The resulting rubber compositions were subjected to measurement of vulcanization rate, green strength and extrusion rate, and the vulcanizates obtained by vulcanizing the rubber compositions at 160°C for 30 min. were subjected to measurement of elongation, hardness, 100 % modulus, 300 % modulus, tensile strength, tear strength, permanent elongation and compression permanent set. The results obtained are shown in Table 8.
Table 8 ______________________________________ Example No. Measurement item 25 26 ______________________________________ Vulcanization rate (CURELASTOMETER) T90 (min, sec) 19'00" 6'45" T90-T10 (min, sec) 17'30" 5'30" Green strength -(at room temperature) Tensile strength (kg/cm 2 ) 7 11 Extrusion rate (cc/min) 293 347 Physical properties of vulcanizate Elongation (%) 380 420 Hardness (JIS Hs) 74 80 100 % modulus (kg/cm 2 ) 48 51 300 % modulus (kg/cm 2 ) 71 73 Tensile strength (kg/cm 2 ) 93 82 Tear strength (kg/cm) 27 33 Permanent elongation (%) 26 25 Compression permanent set (%) 25 23 Remarks Compara- Example tive Example ______________________________________ Note: The conditions of extruder were as follows: Barrel temperature: 70°C Die temperature: 90°C Screw revolution: 30 r.p.m.
EXAMPLE 5
The 1,2-polyburadiene (A) and an ethylenepropylene-dicyclopentadiene terpolymer rubber having a propylene content of 38 % by weight and an iodine number of 15 (referred to hereinafter as EPDM (D)) were mixed with the prescription shown in Table 9 by means of a Banbury's mixer (in the case of vulcanizing system, by means of rolls) to prepare rubber compositions.
Table 9 ____________________________________________________________ ______________ Sample No. 27 28 29 30 31 ____________________________________________________________ ______________ Ingredients blended EPDM (D) (part) 100 95 90 85 70 1,2-Polybutadiene (A) (part) 0 5 10 15 30 Carbon black (HAF) (part) 67.5 67.5 67.5 67.5 67.5 Naphthenic extender oil (part) 35 35 35 35 35 Zinc oxide (part) 5 5 5 5 5 Stearic acid (part) 1 1 1 1 1 Accelerator TS (part) 1.5 1.5 1.5 1.5 1.5 Accelerator M (part) 0.5 0.5 0.5 0.5 0.5 Sulfur (part) 1.5 1.5 1.5 1.5 1.5 Remarks Compara- Examples tive Example ____________________________________________________________ ______________
The resulting rubber compositions were subjected to measurement of vulcanization rate and green strength to obtain the results shown in Table 10.
Table 10 ______________________________________ Sample No. Measurement Item 27 28 29 30 31 ______________________________________ Vulcanization rate (Oscillating disk rheometer) T90 (min, sec) 22'00" 18'12" 17'30" 15'40" 15'15" T90-T10 (min, sec) 13'24" 9'10" 8'48" 8'20" 7'50" Green strength (at room) temperature) Tensile strength 3.1 3.8 3.9 7.2 14.2 (kg/cm 2 ) Elongation 460 450 440 400 440 (%) -(at 50°C Tensile strength 2.1 2.5 3.0 3.9 11.2 (kg/cm 2 ) Elongation 580 500 500 510 540 (%) (at 80°C) Tensile strength 1.3 1.4 1.3 1.4 1.4 (kg/cm 2 ) Elongation 600 540 500 500 520 (%) Remarks Compara- Examples tive Example ______________________________________
COMPARATIVE EXAMPLES
1,2-Polybutadiene having a 1,2-addition unit content of 82.5 %, and an intrinsic viscosity of 0.25 dl/g as measured in toluene at 30°C (crystallinity was impossible to measure) (referred to hereinafter as 1,2-polybutadiene (Y)) or 1,2-polybutadiene having a 1,2addition unit content of 58.3 %, a crystallinity of 0 % and an intrinsic viscosity of 1.15 dl/g as measured in toluene at 30°C (referred to hereinafter as 1,2-polybutadiene (Z)), and the EPDM (A) were mixed with the prescription shown in Table 11 by means of rolls to prepare rubber compositions.
Table 11 ____________________________________________________________ ______________ Sample No. Ingredients blended 32 33 34 35 36 37 ____________________________________________________________ ______________ EPDM (A) (part) 100 95 90 85 90 70 1,2-Polybutadiene (Y) (part) 0 5 10 15 -- -- 1,2-Polybutadiene (Z) (part) -- -- -- -- 10 30 Carbon black (HAF) (part) 67.5 67.5 67.5 67.5 67.5 67.5 Naphthenic extender oil (part) 35 35 35 35 35 35 Zinc oxide (part) 5 5 5 5 5 5 Stearic acid (part) 1 1 1 1 1 1 Accelerator TS (part) 1.5 1.5 1.5 1.5 1.5 1.5 Accelerator M (part) 0.5 0.5 0.5 0.5 0.5 0.5 Sulfur (part) 1.5 1.5 1.5 1.5 1.5 1.5 Remarks Comparative Examples ____________________________________________________________ ______________
The resulting rubber compositions were subjected to measurement of green strength to obtain the results shown in Table 12.
Table 12 ______________________________________ Sample No. Measurement item 32 33 34 35 36 37 ______________________________________ Green strength (at room temperature) Tensile strength 5.0 4.7 4.3 3.8 5.0 4.8 (kg/cm 2 ) Elongation 300 450 520 680 290 280 (%) (at 50°C) Tensile strength 3.4 2.9 2.7 2.5 3.3 3.0 (kg/cm 2 ) Elongation 440 510 620 730 390 400 (%) (at 80°C) Tensile strength 1.3 1.2 1.0 1.0 1.2 1.0 (kg/cm 2 ) Elongation 490 600 690 770 450 420 (%) Remarks Comparative Examples ______________________________________
Commercially available ethylene-propylene rubbers, particularly EPDM are excellent in thermal resistance, ageing resistance, weather resistance and ozone resistance, have good electric properties and good cold brittleness, and are similar to natural rubber particularly in behavior of elastic properties on temperatures. Therefore, the EPDM can be vulcanized with sulfur similarly to conventional rubbers. Further, the EPDM can be produced at considerably low cost as compared with conventional diene rubbers, because the starting materials, ethylene and propylene, for the EPDM are supplied in large amounts and at low cost by petrochemical industry. In addition, the EPDM can be extended with a large amount of oil. Thus, the EPDM is advantageous even in the aspect of economy, and hence, is expected as wide-use rubbers in future. However, the EPDM is greatly disadvantageous in processability, i.e., the vulcanization rate is very low and the stickiness is low. Therefore, EPDM is greatly limited in practical use.
The present inventors have extensive research on EPDM having no such disadvantages to find that by blending the specific 1,2-polybutadiene with the EPDM, the above-mentioned disadvantages of the EPDM are removed, the extrudability of the EPDM is improved, and the rubbery properties of vulcanizate of the EPDM are hardly impaired or rather improved.
An object of this invention is to provide an EPDM composition having improved properties.
A further object of the invention is to provide an EPDM composition having a high vulcanization rate, a high green strength and an excellent processability.
A still further object of the invention is to provide an EPDM composition comprising an EPDM and 1,2-polybutadiene.
Other objects and advantages of the invention will be apparent from the following description.
According to this invention, there is provided an EPDM composition comprising 97 to 50 % by weight of at least one EPDM and 3 to 50 % by weight of at least one 1,2-polybutadiene having a 1,2-addition unit content of at least 70 %, a crystallinity of at least 5 % and an intrinsic viscosity of at least 0.7 dl/g as measured in toluene at 30°C.
The 1,2-polybutadienes used in this invention have a 1,2-addition unit content of at least 70 %, preferably at least 85 %. When the 1,2-addition unit content is less than 70 %, the green strength is too low. Further, the crystallinity of the 1,2-polybutadienes is at least 5 %, preferably 5 to 50 %, particularly preferably 10 to 30 %, in view of ease of mixing. When the crystallinity is less than 5 %, the green strength-improving effect is too small, and the physical properties of the vulcanizate of such a composition are not satisfactory. Furthermore, the 1,2-polybutadienes have an intrinsic viscosity as measured in toluene at 30°C of at least 0.7 dl/g, preferably at least 1.0 dl/g. When the intrinsic viscosity is less than 0.7 dl/g, the green strength of the composition is unsatisfactory, and the physical properties of vulcanizate, particularly modulus, are inferior. 1,2-Polybutadienes satisfying the above-mentioned conditions can be produced by the methods disclosed in U.S. Pat. Nos. 3,498,963 and 3,522,332. The above 1,2-polybutadienes may be used alone or in admixture of two or more, or in admixture with such an amount of other 1,2-polybutadienes as not to impair the effect of the invention.
In this invention, the amount of the 1,2-polybutadienes used is 3 to 50 % by weight based on the weight of the rubber compsotion of this invention. When the amount is more than 50 %, the composition is not desirable in respects of resilience and permanent set. When the amount is less than 3 % by weight, substantially no effect of this invention is obtained.
The EPDM used in this invention may be any of those which are commercially available, though those comprising 50 to 80 % by weight of ethylene, 50 to 20 % by weight of propylene and up to 5 % by weight of diene (corresponding to an iodine number of about 50) are preferably used in general. Typical examples of the diene include 1,4-hexadiene, dicyclopentadiene, 5-methylene- 2-norbornene, 5-ethylidene-2-norbornene, 1,5cyclooctadiene, etc. When the propylene content is less than 30 % by weight, the EPDM per se has a great green strength, and in addition, the vulcanization rate and processability of the EPDM are also improved by blending the 1,2-polybutadienes therewith according to this invention. The EPDM may be used alone or in admixture of two or more.
In this invention, the 1,2polybutadiene and the EPDM may be mixed by any known method, for example, by mixing a solution of the 1,2polybutadiene with a solution of the EPDM and then removing the solvents from the resulting mixture, or by conventionally mechanically mixing the 1,2-polybutadiene with the EPDM each in the form of solid by means of, for example, rolls, Banbury's mixer, kneader-blender, or the like.
It is, of course, possible to incorporate into the rubber composition of this invention at least one conventional compounding ingredient, such as reinforcing agents, fillers, extender oils, pigments, vulcanizing agents, vulcanization accelerators, vulcanization activators, antioxidants, ultraviolet absorbers, blowing agents, odorants, softening agents, etc.
The rubber composition of this invention has a high green strength, a high vulcanization rate and a greatly improved processability, such as high extrusion rate and a high stickiness. Further, the vulcanizate of the rubber composition is greatly excellent in hardness and resistance to crack-growing. In addition, the rubbery properties of the EPDM, for instance, resilience and permanent set, are not so much impaired. Therefore, the rubber composition of this invention can be used as elements which are very useful in industry as novel ethylene-propylene type rubber composition.
The invention is further explained below in more detail referring to the following Examples, which are not by way of limitation, but by way of illustration.
The micro-structures of the 1,2-polybutadienes used in the Examples were measured by the infrared absorption spectrum method of D. Morero et al. (Chimie et Ind., 41, 758 (1959)). The crystallinity was determined by the density measurement method in which the following equation was used: ##EQU1## wherein d: density of the specimen measured at 20°C,
d cr : density of the crystalline region,
d am : density of the amorphous region,
X: crystallinity in per cent.
The value of d cr used was that of the crystalline 1,2-polybutadiene calculated by Natta from X-ray experiments to be 0.963 (G. Natta, J. Polymer Sci., 20, 251 (1956)). The value of d am used was 0.892 or the density of the 1,2-polybutadiene obtained by the synthesizing process proposed in U.S. Pat. No. 3,498,963 and found to be completely amorphous by X-ray analysis. The iodine number of the EPDM was determined by the following equation: ##EQU2## In the examples, parts are by weight unless otherwise specified.
EXAMPLE 1
1,2-Polybutadiene having a 1,2-addition unit content of 92.0 %, a crystallinity of 25 % and an intrinsic viscosity of 1.30 dl/g as measured in toluene at 30 °C (referred to hereinafter as 1,2-polybutadiene (A) and an ethylene-propylene-5-ethylidene-2-norbornene terpolymer rubber having a propylene content of 43 % by weight and an iodine number of 15 (referred to hereinafter as EPDM (A)) were mixed by a Banbury's mixer (in the case of vulcanizing system, they were mixed by rolls) with the prescription shown in Table 1 to prepare rubber compositions.
Table 1 ____________________________________________________________ ______________ Sample No. Ingre- 1 2 3 4 5 6 dients blended ____________________________________________________________ ______________ EPDM (A) (part) 100 95 90 85 70 60 1,2-Polybutadiene (A) (part) 0 5 10 15 30 40 Carbon black (HAF) (part) 67.5 67.5 67.5 67.5 67.5 67.5 Naphthenic extender oil 35 35 35 35 35 35 (part) Zinc oxide (part) 5 5 5 5 5 5 Stearic acid (part) 1 1 1 1 1 1 Accelerate CZ (N-cyclo- hexyl-2-benzothiazyl- 2.5 2.5 2.5 2.5 2.5 2.5 sulfenamide) (part) Sulfur (part) 1.5 1.5 1.5 1.5 1.5 1.5 ____________________________________________________________ ______________ Remarks Com- para- tive Examples Ex- ample ____________________________________________________________ ______________
The resulting rubber compositions were subjected to measurement of vulcanization rate, green strength, extrusion rate, and die shrinkage, and vulcanizates obtained by vulcanizing the rubber compositions at 160°C for 15 min. were subjected to measurement of various physical properties to obtain the results shown in Table 2.
Table 2 ____________________________________________________________ ______________ Sample No. Measure- 1 2 3 4 5 6 ment item ____________________________________________________________ ______________ Vulcanization Rate (Oscillating disk rheometer) T90 (min. sec) 15'24" 14'12" 13'24" 12'42" 11'48" 11'12" T90-T10 (min, sec) 10'05" 9'28" 8'12" 7'26" 6'00" 5'28" Green strength (at room temperature) 100 % modulus (kg/cm 2 ) 3.7 5.3 7.0 8.4 13.5 20.0 (Tensile strength (kg/cm 2 ) 4.3 5.8 7.5 9.6 17.1 29.1 Elongation (%) 400 390 380 380 380 390 (at 40°C) 100 % modulus (kg/cm 2 ) 2.9 3.1 3.5 4.2 8.0 13.0 Tensile strength (kg/cm 2 ) 3.7 3.8 3.9 4.8 9.9 17.2 Elongation (%) 410 390 360 370 410 420 (at 80°C) 100 % modulus (kg/cm 2 ) 1.1 1.2 1.3 1.6 2.6 3.5 Tensile strength (kg/cm 2 ) 1.5 1.6 1.6 1.9 3.5 4.8 Elongation (%) 390 360 340 340 330 310 Extrusion test (1) Extrusion rate (cc/min) 244.0 265.0 290.5 288.0 271.0 -- Die shrinkage (%) 41.7 41.5 41.0 40.5 40.3 -- Physical properties of vulcanizate 300 % modulus (kg/cm 2 ) 130 131 133 134 138 142 Tensile strength (kg/cm 2 ) 183 187 189 186 166 168 Elongation (%) 410 420 420 410 370 360 Hardness (JIS Hs) 69 71 73 74 77 79 Tear strength (kg/cm) 49 53 54 54 55 57 Resilience (%) 47 42 38 35 27 28 Compression permanent set (%) 18 18 18 19 21 25 Crack-growing (2) 500 times 5.3 -- 2.8 -- 4.1 -- 1000 times 9.3 -- 4.2 -- 5.7 -- 3000 times 15.4 -- 8.8 -- 9.7 -- ____________________________________________________________ ______________ Remarks Compara- Examples tive Example ____________________________________________________________ ______________ Note: (1) Extruder conditions were as follows: Barrel temperature: 70°C Die temperature: 105°C Screw revolution: 21 rpm (2) Numerals show the lengths of cracks (mm).
EXAMPLE 2
The 1,2-polybutadiene (A) and the EPDM (A) used in Example 1 were mixed with the prescription shown in Table 3 by means of a Banbury's mixer (in the case of vulcanizing system, they were mixed by rolls) to obtain rubber compositions.
Table 3 ____________________________________________________________ ______________ Sample No. Ingre- dients 7 8 9 10 11 blended ____________________________________________________________ ______________ EPDM (A) (part) 100 95 90 85 70 1,2-Polybuta- diene (A) (part) 0 5 10 15 30 Carbon black (HAF) (part) 67.5 67.5 67.5 67.5 67.5 Naphthenic extender oil (part) 35 35 35 35 35 Zinc oxide (part) 5 5 5 5 5 Stearic acid (part) 1 1 1 1 1 Accelerator TS (tetramethylthiuram monosulfide) (part) 1.5 1.5 1.5 1.5 1.5 Accelerator M (2-mercaptobenzo- thiazole) (part) 0.5 0.5 0.5 0.5 0.5 Sulfur (part) 1.5 1.5 1.5 1.5 1.5 ____________________________________________________________ ______________ Remarks Compara- tive Ex- Examples ample ____________________________________________________________ ______________
The resulting rubber compositions were subjected to measurement of vulcanization rate, green strength and extursion rate to obtain the results shown in Table 4.
Table 4 ____________________________________________________________ ______________ Sample No. 7 8 9 10 11 Measurement item ____________________________________________________________ ______________ Vulcanization rate (Oscillating disk rheometer) T90 (min, sec) 11'00" 8'06" 8'06" 7'24" 7'48" T90-T10 (min, sec) 6'24" 4'06" 3'48" 3'36" 4'24" Green strength (at room temperature) Tensile strength (kg/cm 2 ) 5.3 5.8 5.9 7.0 14.8 Elongation (%) 290 220 210 200 220 (at 50°C) Tensile strength (kg/cm 2 ) 3.5 4.0 4.4 4.8 11.0 Elongation (%) 420 330 300 200 260 (at 80°C) Tensile strength (kg/cm 2 ) 1.2 1.2 1.2 1.3 1.4 Elongation (%) 470 430 360 340 240 Extrusion rate (1) (cc/min) 180.3 198.4 202.3 205.6 212.5 Remarks Compara- Examples tive Example ____________________________________________________________ ______________ (1) Extruder conditions were as follows: Barrel temperature: 70°C Die temperature: 110°C Screw revolution: 21 rpm.
EXAMPLE 3
The 1,2-polybutadiene (A) used in Example 1, 1,2-polybutadiene having a 1,2-addition unit content of 89.7 %, a crystallinity of 15 % and an intrinsic viscosity of 1.85 dl/g as measured in toluene at 30°C (referred to hereinafter as 1,2-polybutadiene (B)), 1,2-polybutadiene having a 1,2-addition unit content of 86.7 %, a crystallinity of 0 % and an intrinsic viscosity of 2.05 dl/g as measured in toluene at 30°C (hereinafter referred to as 1,2-polybutadiene (X)) for comparison, the EPDM (A) used in Example 1 and an ethylene-propylene-5-ethylidene- 2-norbornene terpolymer rubber having a propylene content of 27 % by weight, and an iodine number of 15 (referred to hereinafter as EPDM (B)) were used in amounts shown in Table 5. These components were mixed with the prescription shown in Table 5 by means of a Banbury's mixer (in the case of vulcanizing system, by means of rolls) to prepare rubber compositions.
Table 5 ____________________________________________________________ ______________ Sample No. 7 12 13 14 15 16 17 18 19 20 21 22 23 24 Ingredients blended ____________________________________________________________ ______________ EPDM (A) (part) 100 90 90 90 70 70 70 -- -- -- -- -- -- -- EPDM (B) (part) -- -- -- -- -- -- -- 100 90 90 90 70 70 70 1,2-Polybuta- -diene (A) (part) -- 10 -- -- 30 -- -- -- 10 -- -- 30 -- -- " (B) (part) -- -- 10 -- -- 30 -- -- -- 10 -- -- 30 -- " (X) (part) -- -- -- 10 -- -- 30 -- -- -- 10 -- -- 30 Carbon black (HAF) (part) 67.5 Naphthenic extender oil (part) 35 Zinc oxide (part) 5 Stearic acid (part) 1 The same as left Accelerator TS (part) 1.5 Accelerator M (part) 0.5 Sulfur (part) 1.5 ____________________________________________________________ ______________ Remarks Comp Example Comp. Example Comp. Example Comp. Example Comp. Ex. Ex. Ex. Ex. Ex. ____________________________________________________________ ______________
The resulting rubber compositions were subjected to measurement of vulcanization rate, and green strength, and the vulcanizates obtained by vulcanizing the compositions at 160°C for 30 min. were subjected to measurement of hardness, crack-growth, resilience, and compression permanent set. The results obtained are shown in Table 6.
Table 6 ____________________________________________________________ ______________ Sample No. Measure- ment items 7 12 13 14 15 16 17 18 19 20 21 22 23 24 ____________________________________________________________ ______________ Vulcaniz- ation rate (Oscillat- ing disk rheometer) T90 11'00" 8'06" 8'00" 7'30" 8'18" 8'54" 7'48" 11'24" 8'24" 7'54" 6'30" 8'48" 9'00" 7'42" min, sec) T90-T10 6'24" 3'48" 3'36" 3'30" 4'00" 4'36" 4'06" 4'42" 3'42" 3'24" 2'12" 4'00" 4'10" 3'48" (min, sec) Green strength (at room temp.) Tensile strength (kg/cm 2 ) 5.3 5.9 5.4 4.9 13.0 8.6 5.0 34 30 32 32 29 29 28 Elongation -(%) 290 210 240 290 100 250 270 1150 1160 1200 1220 430 1090 1360 (at 50°C) Tensile strength (kg/cm 2 ) 3.5 2.8 2.6 2.6 7.1 3.3 2.6 3.0 4.2 3.8 2.7 8.2 4.0 2.4 Elongation (%) 420 300 340 320 120 280 340 340 260 280 300 120 260 260 at (80°C) Tensile strength (kg/cm 2 ) 1.2 1.2 1.2 1.2 2.1 1.2 1.3 1.7 1.7 1.7 1.5 2.8 1.7 1.5 Elongation (%) 470 360 420 460 220 300 380 380 340 320 320 180 260 260 Physical properties of vulcan- -izate Hardness (JIS Hs) 70 73 74 75 78 75 75 70 75 76 75 79 77 77 Crack- growth* 100 times 0.9 0.2 0.2 0.2 -- -- -- 3.7 -- -- -- 0.4 0.6 0.7 1000 times 5.2 0.7 0.6 0.8 -- -- -- 11.0 -- -- -- 1.1 1.4 1.6 10000 times 15.3 3.3 2.6 3.7 -- -- -- ** -- -- -- 5.3 6.0 16.9 Resilience (%) 50 36 38 41 35 36 41 58 42 43 45 40 41 45 Compress- ion perm- anent set (%) 26 25 27 27 31 32 31 33 21 19 20 24 33 27 30 ____________________________________________________________ ______________ Remarks Comp. Example Comp. Example Comp. Example Comp. Example Comp. Ex. Ex. Ex. Ex. Ex. ____________________________________________________________ ______________ Note: *Numerals refer to lengths of cracks (mm). **Totally cracked.
EXAMPLE 4
1,2-Polybutadiene having a 1,2-addition unit content of 92.0 %, a crystallinity of 24 % and an intrinsic viscosity of 1.57 dl/g as measured in toluene at 30°C (referred to hereinafter as 1,2-polybutadiene (C)) and an ethylene-propylene-5-ethylidene-2-norbornene terpolymer rubber having a propylene content of 42 % by weight and an iodine number of 20 (referred to hereinafter as EPDM (C)) were mixed with the prescription shown in Table 7 by means of a Banbury's mixer (in the case of vulcanizing system, by means of rolls) to prepare rubber compositions.
Table 7 ______________________________________ Sample No. Ingredients blended 25 26 ______________________________________ EPDM (C) (part) 100 90 1,2-Polybutadiene (C) (part) 0 10 Carbon black (HAF) (part) 5 5 Magnesium silicate (part) 60 60 Hard clay (part) 60 60 Naphthenic extender oil (part) 6 6 Paraffin wax (part) 5 5 Zinc oxide (part) 5 5 Stearic acid (part) 1 1 Accelerator M (part) 2 2 "TT (tetramethylthiuram disulfide) (part) 0.5 0.5 Accelerator TRA (dipentamethylenethiuram (tetrasulfide) (part) 0.75 0.75 Sulfur (part) 1.5 1.5 Remarks Compara- Example tive Example ______________________________________
The resulting rubber compositions were subjected to measurement of vulcanization rate, green strength and extrusion rate, and the vulcanizates obtained by vulcanizing the rubber compositions at 160°C for 30 min. were subjected to measurement of elongation, hardness, 100 % modulus, 300 % modulus, tensile strength, tear strength, permanent elongation and compression permanent set. The results obtained are shown in Table 8.
Table 8 ______________________________________ Example No. Measurement item 25 26 ______________________________________ Vulcanization rate (CURELASTOMETER) T90 (min, sec) 19'00" 6'45" T90-T10 (min, sec) 17'30" 5'30" Green strength -(at room temperature) Tensile strength (kg/cm 2 ) 7 11 Extrusion rate (cc/min) 293 347 Physical properties of vulcanizate Elongation (%) 380 420 Hardness (JIS Hs) 74 80 100 % modulus (kg/cm 2 ) 48 51 300 % modulus (kg/cm 2 ) 71 73 Tensile strength (kg/cm 2 ) 93 82 Tear strength (kg/cm) 27 33 Permanent elongation (%) 26 25 Compression permanent set (%) 25 23 Remarks Compara- Example tive Example ______________________________________ Note: The conditions of extruder were as follows: Barrel temperature: 70°C Die temperature: 90°C Screw revolution: 30 r.p.m.
EXAMPLE 5
The 1,2-polyburadiene (A) and an ethylenepropylene-dicyclopentadiene terpolymer rubber having a propylene content of 38 % by weight and an iodine number of 15 (referred to hereinafter as EPDM (D)) were mixed with the prescription shown in Table 9 by means of a Banbury's mixer (in the case of vulcanizing system, by means of rolls) to prepare rubber compositions.
Table 9 ____________________________________________________________ ______________ Sample No. 27 28 29 30 31 ____________________________________________________________ ______________ Ingredients blended EPDM (D) (part) 100 95 90 85 70 1,2-Polybutadiene (A) (part) 0 5 10 15 30 Carbon black (HAF) (part) 67.5 67.5 67.5 67.5 67.5 Naphthenic extender oil (part) 35 35 35 35 35 Zinc oxide (part) 5 5 5 5 5 Stearic acid (part) 1 1 1 1 1 Accelerator TS (part) 1.5 1.5 1.5 1.5 1.5 Accelerator M (part) 0.5 0.5 0.5 0.5 0.5 Sulfur (part) 1.5 1.5 1.5 1.5 1.5 Remarks Compara- Examples tive Example ____________________________________________________________ ______________
The resulting rubber compositions were subjected to measurement of vulcanization rate and green strength to obtain the results shown in Table 10.
Table 10 ______________________________________ Sample No. Measurement Item 27 28 29 30 31 ______________________________________ Vulcanization rate (Oscillating disk rheometer) T90 (min, sec) 22'00" 18'12" 17'30" 15'40" 15'15" T90-T10 (min, sec) 13'24" 9'10" 8'48" 8'20" 7'50" Green strength (at room) temperature) Tensile strength 3.1 3.8 3.9 7.2 14.2 (kg/cm 2 ) Elongation 460 450 440 400 440 (%) -(at 50°C Tensile strength 2.1 2.5 3.0 3.9 11.2 (kg/cm 2 ) Elongation 580 500 500 510 540 (%) (at 80°C) Tensile strength 1.3 1.4 1.3 1.4 1.4 (kg/cm 2 ) Elongation 600 540 500 500 520 (%) Remarks Compara- Examples tive Example ______________________________________
COMPARATIVE EXAMPLES
1,2-Polybutadiene having a 1,2-addition unit content of 82.5 %, and an intrinsic viscosity of 0.25 dl/g as measured in toluene at 30°C (crystallinity was impossible to measure) (referred to hereinafter as 1,2-polybutadiene (Y)) or 1,2-polybutadiene having a 1,2addition unit content of 58.3 %, a crystallinity of 0 % and an intrinsic viscosity of 1.15 dl/g as measured in toluene at 30°C (referred to hereinafter as 1,2-polybutadiene (Z)), and the EPDM (A) were mixed with the prescription shown in Table 11 by means of rolls to prepare rubber compositions.
Table 11 ____________________________________________________________ ______________ Sample No. Ingredients blended 32 33 34 35 36 37 ____________________________________________________________ ______________ EPDM (A) (part) 100 95 90 85 90 70 1,2-Polybutadiene (Y) (part) 0 5 10 15 -- -- 1,2-Polybutadiene (Z) (part) -- -- -- -- 10 30 Carbon black (HAF) (part) 67.5 67.5 67.5 67.5 67.5 67.5 Naphthenic extender oil (part) 35 35 35 35 35 35 Zinc oxide (part) 5 5 5 5 5 5 Stearic acid (part) 1 1 1 1 1 1 Accelerator TS (part) 1.5 1.5 1.5 1.5 1.5 1.5 Accelerator M (part) 0.5 0.5 0.5 0.5 0.5 0.5 Sulfur (part) 1.5 1.5 1.5 1.5 1.5 1.5 Remarks Comparative Examples ____________________________________________________________ ______________
The resulting rubber compositions were subjected to measurement of green strength to obtain the results shown in Table 12.
Table 12 ______________________________________ Sample No. Measurement item 32 33 34 35 36 37 ______________________________________ Green strength (at room temperature) Tensile strength 5.0 4.7 4.3 3.8 5.0 4.8 (kg/cm 2 ) Elongation 300 450 520 680 290 280 (%) (at 50°C) Tensile strength 3.4 2.9 2.7 2.5 3.3 3.0 (kg/cm 2 ) Elongation 440 510 620 730 390 400 (%) (at 80°C) Tensile strength 1.3 1.2 1.0 1.0 1.2 1.0 (kg/cm 2 ) Elongation 490 600 690 770 450 420 (%) Remarks Comparative Examples ______________________________________